I assume you are embedding one form on many pages (or custom posts). It is possible to have Gravity Forms capture the ID of the referring page, as well as know it’s Title. This is helpful in the email notification, for example, to understand on what page a contact was on when they decided to make contact. IE a form that is on every page… but what prompted them to finally fill it out?
With this same information, you can reference the referring page in order to cross reference that with a list comprised of the titles/names of the people who sent information while on that page.
Even if you didn’t capture that data in the beginning, I am fairly certain that information is inside the actual gravity form lead description meta, in the database. Probably from that you would be able to access the relationship of submitter -> referring page.
Otherwise I would have it saved as post_meta in the future, as part of the post, so you don’t have to dip into gforms tables.
Documentation on this hook will help: Gform after submission – GravityForms